Knobby ones, hairy ones, individuals with algae-like appendages—frogfish are true masters of underwater camouflage. They can sit extremely still, blend in with the seafloor, and pretend to be a sea sponge, coral, or rock. Some can even change colour, chameleon-like, though the process may take weeks.
Though they are fish, they have the rough, knobbly look of frogs, and pectoral fins that look like frog’s legs. Unlike most other fish, they don’t possess a swim bladder. To move from place to place, they do two things: They move these modified pectoral fins in a half-waddle, half-swim motion along the floor, and also gulp large quantities of water and rush them out of their gills, to propel themselves through the ocean.
The carnivorous frogfish are clever predators with a unique hunting adaptation and strategy. They start by slowly moving into an area where there is prey and sitting patiently, motionless, for a long time until the other fish forget they are around. Frogfish have a rod-like appendage called an illicium in front of the dorsal fin atop their heads. At the end of the illicium is a lure, the esca, which looks like a worm or shrimp, depending on the species. Using this, it baits its prey. Once the frogfish has established its camouflage amidst the coral, rocks, or other creatures of the sea, it slowly starts to jiggle its ‘fishing-rod’. An interested fish approaches the esca, which looks like the perfect meal. In as little as six milliseconds, the frogfish opens its highly flexible jaw wide, and creates a vacuum that sucks the surrounding seawater in. The unsuspecting fish is pulled in and swallowed whole. This ability of ‘angling’ for prey has given the frogfish its other name—anglerfish.
There are many varieties of frogfish; approximately 45 species have been documented. Some live so far below the surface that sunlight never reaches them, and they have bioluminescent lures at the end of their illicium to attract prey. The yellow frogfish pictured in this story is one that can be seen by divers and snorkellers in shallow waters.
Most frogfish species reproduce through a method called free spawning. A female anglerfish gives off a powerful chemical scent which leaves a trail in the water. A male senses and follows the chemical trail, then prods the female to lay thousands of eggs in a mass of mucous, in open water. The male then releases sperm to fertilize them. Some frogfish display sexual parasitism, an unusual kind of reproduction. In these species of anglerfish, males are very tiny and don’t have the fishing lure to feed themselves. Their primary goal in this case is to find a female and fuse with her. Once they meet, the male anglerfish bites into the female’s body, holding on until it has fused with her. The male anglerfish now becomes a constant source of sperm for the female to fertilize her eggs. In return, he receives the nutrition to survive. With this strange coupling of convenience, this species of frogfish multiplies.
Some species of anglerfish can grow upto 40 cm long, but most are much smaller, usually averaging 5-10 cm in length. Because they are so good at camouflage and hiding they have survived very well and are not a threatened species.
SPOT THEM:
Scuba diving is the only way to spot these fish in their natural environment. The tropical waters of Indonesia, especially the Lembeh strait, are famous for many species of frogfish, though they can be seen at almost all the top dive sites of Asia and the Pacific, as well as in parts of the Caribbean.
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